A novel NiO/CeO2-mSiO2 nanocages with peroxidase-mimetic activity for ultra-sensitive biosensing

Abstract

A novel NiO/CeO2−mSiO2 nanocages with superior peroxidase−like activities due to the synergetic effect between NiO and CeO2 were fabricated by a simple etching−precipitation method with core−shell structured Cu2O@mSiO2 as a sacrificial template. Based on the peroxidase−like activity of the NiO/CeO2−mSiO2 nanocages, an enzyme cascade−triggered colorimetric sensing platform was exploited for alkaline phosphatase (ALP) detection, owing to the fact that ascorbic acid (AA) that is the ALP enzymatic hydrolysis product of ascorbic acid 2−phosphate (AAP) can efficiently reduce the oxidation product of TMB (oxTMB) generated under the catalysis of the NiO/CeO2−mSiO2. For the sensing of ALP, a good linear response was observed in the range of 0.0005–1.25 mU mL−1 with the limit of detection (LOD) as low as 0.00048 mU mL−1. Furthermore, the proposed enzyme cascade−triggered colorimetric sensing platform could be further explored for sensing of tyrosinase, according to the fact that dopamine (DA) the catalytic product of tyramine (Tyr) by tyrosinase could initiate the redox reaction with the oxTMB acquired under the catalysis of the NiO/CeO2−mSiO2. A wide linear response was found for tyrosinase detection from 0.02 mU mL−1 to 3.4 U mL−1 with a LOD as low as 0.002 U mL−1. This work not only offers a facile and effective approach to fabricate nanozymes with excellent catalytic activity, but also provides a promising enzyme cascade−triggered colorimetric method for the ultra−sensitive detection of biological enzymes.